When a concrete contractor is asked to pour a sidewalk, concrete pad, or floor, once the plastic concrete has been poured into its forms and raked level, the contractor must produce a flat, uniform surface that is structurally sound and satisfactory to the customer.
Concrete “flatwork” is a universal process where, first, the concrete contractor pours plastic concrete into forms, then levels the plastic concrete using hand labor. Hand labor is used to place and roughly level the plastic concrete using tools called come-alongs or rakes. The next step is called “striking” the concrete. Concrete is “struck” using a screed; it is given a flat, level surface using a horizontally-aligned bar of some type to pull and level the freshly poured plastic concrete surface into a plane.
Traditionally, striking can be achieved using two different approaches dictated by availability of tools, labor, and the individual preference of the concrete contractor. Screed bars and motorized vibratory screeds are the two choices for striking concrete.                1. Screed bars: 2×4 s aligned horizontally and used in planar fashion with the 2″ surface contacting the concrete and worker(s) gripping the 4″surface vertically.                    a. A 2×4 screed bar of wood or metal and sized to the specific job is typically used by a team of 2 workers who grip the 2×4 and drag the plastic concrete into a level surface within forms. A screed bar can also be used by a single individual, but productivity is decreased as compared to that of a two-person team due to the increased physical effort required. The screed bar is used to screed and strike, using multiple lifting and dragging motions to smooth and level the plastic concrete within the forms. In this non-motorized process, individuals hold directly onto the screed bar 2×4 in a stooped posture, manually moving the screed bar. Using screed bars in this fashion is a common source of back and or arm strain or injury. There are tools which have been created which aid the operator of the 2×4 screed bar in holding onto it either in stooped postures or standing postures.            b. Vice-like attachments with handles allow the strikers using the stoop and drag method to hold onto the bar with less difficulty.            c. Long-handled attachments can be employed to allow the individuals to stand upright and drag the 2×4 screed bar across the concrete in the striking process. This piece of equipment is called a “standing screed”.                        2. Vibratory, motorized, manual standing screeds have been invented to introduce vibration into the screed bar to increase the standing screed's effectiveness. It vibrates the concrete to strike it quickly into a flat surface. Motorized vibratory screeds employ an attached motor to induce vibration to smooth and level the plastic concrete and increase the strength of the finished concrete with the increased consolidation of the aggregate obtained by vibration; (lasers are sometimes utilized on motorized screeds to aid the operator in obtaining a level surface). Some motorized vibratory screeds exist that require forms, some, only a wet bench (floating screeds), and some, which utilize lasers, require no “bench” to rest upon to produce the desired product. Motorized vibratory screeds of any type are highly technical pieces of equipment, which are costly, heavy, and require working technical knowledge of the specific tool used.        
The present invention revolutionizes the non-motorized screeding and striking process in a simple harmonization of physics and ergonomics. Before describing the present invention, the disadvantages of the above-described concrete screeding and striking processes will be discussed.
The traditional manual screeding technique described above is laborious, and frustrating at times, as well. The hand-held 2×4 is cheap and easy to transport, requires little maintenance or repair, but requires a skilled worker or workers working in tandem with each other with an almost mind-reading quality to work in a rhythm in order to obtain an acceptable concrete surface. These concrete workers must also have exceedingly high abilities to protect their necks, arms and backs from injury due to the awkward positioning and repetitive movements required to strike the concrete in this way.
Standing improves the operator's ergonomics but the device can only screed the concrete without the ability to introduce vibration into the concrete without the addition of a motor strapped to the device.
The motorized floating vibratory screed is expensive, often highly technical, and heavy.
Transportation of large screeds for larger pours becomes an issue for a small-business contractor who often operates with a skeleton crew. The expense of moving a heavy, unwieldy piece of equipment like a motorized screed must be considered. Larger vehicles with winch capabilities increase cost. The process of loading the equipment is a safety concern, as well. Electronic equipment requires expensive repairs and oftentimes, extensive down time. Motors require fuel, oil and maintenance. The time and monetary cost of training employees to learn the proper operation of the instrument also must be considered. All of these factors can greatly increase frustration and decrease productivity if any one fails at any given time.
It is an object of the present invention to provide an ergonomic non-motorized vibratory concrete screed that can be wielded by a single person in order to achieve a superior concrete surface with the least amount of stress to the body and the highest amount of satisfaction to the customer.
The present invention is a small, disassemble-able device that can be built inexpensively, transported easily, used by one man to provide excellent results in projects ranging from sidewalks to driveways to basement floors and patios. Basically, the present invention is designed primarily for residential to small commercial concrete work. By changing attachments it can be modified into a two-person-operated device for larger pours, if desired.
The present invention differs from the previously discussed screeding and striking devices in that its screeding surface is not a single bar, but a floating double bar screeding-striking “plate”. Its screeding-striking plate is not a single vertically aligned bar as used in the manual screeding described above, but double bars oriented in a planar fashion. It is this screeding-striking plate with double 4″ surfaces which is in contact with the concrete, not a 2″ wide screed bar surface as described in the previous standing screed devices. This design allows the screeding-striking plate surface to physically modify concrete by screeding and also introduces vibration accomplished by intermittent pulls on the handle which rock and slide the planar bars over the wet concrete.
As the leading screed bar of the floating strike plate contacts the plastic concrete surface and begins the leveling process (the operator proceeds to make repetitive short, sharp pulls while walking slowly backward) the second plate catches the surface and “finishes” the leveling process. Working as a unit, double screed bar plate of the present invention allows 2 bars to act in tandem, producing vibration similar to a motorized vibrating screeding device. The plastic concrete is vibrated and, therefore, its mass is consolidated while its surface is leveled.
The operator of the present invention is subjected to a very manageable amount of physical exertion as the operator's position is standing, and the action is one of pulling on handles extending from the screed plate assembly at waist level. The base plates of the screed plate assembly have adjustable 45° angle connections. This allows the operator to hold a U-shaped handle at a comfortable waist-level height while making short, repetitive pulling motions generated with minimal effort. By using multiple major muscle groups, legs, abdominals, thoracic, back and arm muscles, no one single group of muscles is overtaxed. A superior surface and concrete strength is achieved with a satisfactory ease of tool use.
It is a further object of the present invention to provide an ergonomic that is easily assembled, transported and stored and is light-weight.
A further object of the invention is to provide an ergonomic non-motorized vibratory concrete screed that may be easily modified to suit the size of any concrete pour.
Yet another object of the present invention to provide an ergonomic non-motorized vibratory concrete screed that is economical, due to simple and easily interchangeable parts without need for power tools to do so.
A further object of the present invention to provide an ergonomic non-motorized vibratory concrete screed that can be used in combination with screed equipment possibly already owned by the contractor.
A still further object of the present invention to provide an ergonomic non-motorized vibratory concrete screed that is ergonomic, not fatiguing a single muscle group in isolation.
Another further object of the present invention to provide an ergonomic that lays very flat, uniform concrete due to the total area of floating strike-plates on contact with the plastic concrete during use and vibration.
A further object of the present invention to provide an ergonomic non-motorized vibratory concrete screed that does not require a motor and is low maintenance.
A further object of the present invention to provide an ergonomic non-motorized vibratory concrete screed that floats on a “wet bench” requiring less form work.